Rotary switch



July 9, 1957 D. G. KIMBALL ROTARY SWITCH Filed sept. 2o, 1954 Amma HMO

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RGTARY SWITCH Donaid G. Kimball, Stratford, Conn., assignor to General Electric Company, a corporation of New York Application September 20, 1954, Serial No. 457,134

6 Claims. (Clt 200-167) This invention relates to a rotary switch of the type frequently used to control the heat given off by electric range heating elements. More particularly, the invention relates to a rotary switch in which a pilot light and rotatable elements may be readily placed in position from the front.

Multi-position rotary switches have generally been provided with a solid center shaft. It is desirable to have a pilot light which is turned on whenever any of the switch contacts are closed. In the past, rotary range switches which include pilot lights have positioned the lights in places which are relatively inaccessible after the switch is mounted in position. In many cases, pilot lights are so inaccessible that they are not replaced after burning out. This increases the likelihood that a switch will be left in the on position when it is no longer needed thereby creating an unnecessary current drain and, at high heats, a fire hazard.

It is one object of this invention to provide a multiposition rotary switch having a pilot light which may be replaced from the outward-facing side of the switch.

It is another object of this invention to provide a camoperated rotary switch in which the cams may be positioned after the contacts are in place on the switch.

It is a further object of the invention to provide a sheet metal sleeve or cam liner which is rotatable to set the position of the actuating cams.

Other objects and features of the invention will become apparent from the following specification considered in conjunction with the annexed drawing wherein Fig. l is a cutaway perspective view of a rotary switch constructed in accordance with this inventions; Fig. 2 is a plan view of the switch with the turning knob, cover plate, and pilot light removed; Fig. 3 is a perspective view of the sheet metal sleeve or liner element of the rotary switch of this invention; and Fig. 4 is a cutaway plan View of the switch with the turning knob removed showing the operation of the indexing springs.

Briefly stated, in accordance with one of its aspects, this invention is directed to a rotary switch comprising a housing, a lamp socket mounted in the base of the housing, a plurality of movable cam-operated spring contact switch members mounted in the housing, a cylindrical cam of non-conducting material rotatable around the lamp socket in engageable relation with the spring contact members, a sheet metal liner for the cylindrical cam, and a cover plate for the housing having a central aperture through which the sheet metal liner protrudes, the cover plate serving to retain the cam and sheet metal liner in rotatable position within the housing, the cam and sheet metal liner being positionable after the spring contact switch members have been placed in position.

Referring to Figs. l and 2, a housing has a lamp socket 11 centrally positioned on an integral base 12 thereof. Also mounted on the base 12 are a plurality of xed contact elements 13 each of which has an associated spring contact element 14 positioned to be operated by a rotatable cam surface 16 mounted on a sheet metal United States Patent O ice liner 17 rotatably mounted on a non-conducting bearing surface 18 coaxial with the lamp socket 11 and integral with the housing base 12. Each of the spring contact elements 14 may have a cam-follower surface 19 and the cam surface 16 may be composed of a plurality of individual cams 21, 22, and 23 and an indexing cam 24.

The contact elements are positioned by means of'rivets 2S extending through the housing base 12. The contact elements include a plurality of terminal screws 26 accessible froin the back portion of the housing 1t).

The sheet metal liner or sleeve 17 has a longitudinal slot 27 which serves the purpose of indexing the cams 21-24. The indexing cam 24 together with a portion of the liner 17 extends above the surface of the housing 10. These elements protrude through a central aperture in an insulating cover plate 28 which is retained in position by a retaining cover plate 29 in spaced relation therewith. The retaining cover plate 29 has a central aperture through which the sheet metal liner 17 extends, the interior surface of the cover plate 29 engaging the side of the indexing cam 24 to retain the cams 21--24 in position against thte housing base 12. The indexing cam 24 is positioned within the space between the insulating cover plate 2% and retaining cover plate 29. This space is also occupied by a pair of indexing springs 31 maintained in position by the shoulders produced by cutaway portions 32 of the retaining cover plate 29. The spring members 31 have oppositely disposed detent nubs 33 (Fig. 4) which follow the surface of the indexing cam 24 in order to provide the plurality of settings for the established contact opening pattern of the cams 21-23. Both of the cover plates 2S and 29 are held in position by means of screws 34.

A pilot lamp 35 screwed into the socket 11 and turning knob 36 press-fitted over the sheet metal liner 17 complete the rotary switch assembly. If the turning knob 36 is of semi-transparent material, a portion of the light given off by the pilot lamp 3S will pass through it and be visible to an observer. if the turning knob 36 is of opaque material, it may be provided with a plurality of apertures in register with apertures 37 in the sheet metal liner 17 to provide a means for observing when the pilot lamp 35 is energized.

While no sequence of contact opening and closing operations has been set forth, it is obvious that the surfaces of the cams 21-2-3 may be scored to provide for any desired sequence. A switch of the type described having relatively small dimensions can readily accommodate eight positions to provide an off setting and seven different heats for an electric range or hotplate. It is obvious that the switch may be used for electrical apparatus other than ranges. In order to replace the pilot lamp 35, it is only necessary to disengage the turning knob 36, remove the defective lamp 35 from the open end of the sheet metal liner 17, and replace with a new lamp. To remove the cams .2l- 24 and sheet metal liner 17, it is only necessary to unscrew the cover plate screws 34, remove the cover plates 28 and Z9, and withdraw the liner 17 with its assembled cams 2i-2fi- Thus, it may be seen that the inner workings of the switch contacts may be quickly exposed to check for a defective condition.

While the invention has been described with reference to a specific embodiment thereof, it is obvious that many variations may be made without departing from the spirit of the invention. Therefore, it is not the intention to limit the invention other than as may be necessitated by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A rotary switch comprising a housing, a lamp socket mounted in the base of said housing, a plurality of movable cam-operated spring contact switch members mounted in said housing, a cylindrical cam of non-conducting material rotatable around said lamp socket in engageable relation with said spring contact members, said cam having a surface contoured to establish a closing pattern for said spring Contact members upon rotation of said cam, a sheet metal liner lixed within the cylindrical cam to support the cam for rotatable movement from the base of the housing, and a cover plate for said housing having a close-fitting central aperture through which said sheet metal liner protrudes, said cover plate serving as a bearing for the liner as well as to retain combined earn and sheet metal liner against the base of said housing, said cam and sheet metal liner assembly being separate from the lamp socket and positionable with said spring contact switch members already in place.

2. A rotary switch as claimed in claim 1 wherein a turning knob is mounted on the sheet metal liner.

3. A rotary switch as claimed in claim 1 wherein a lamp is mounted in said socket and is positioned Within the sheet metal liner.

4. A rotary switch comprising a housing having a recessed base and open top, a lamp socket mounted in the base of said housing, a rotatable sheet metal sleeve surrounding said lamp socket and spaced therefrom, said sleeve extending above the top of said housing, an indexing cam and a plurality of switch-operating cams of nonconducting material mounted on said sleeve and supsaid ported-on a bearing in the base'of the housing, aplurality of spring-contact switch elements mounted in said housing, each of said switch elements being engageable with one of said switch-operating cams whereby the contacts follow a particular closing pattern upon rotation of said cams, an insulating cover plate for said housing having a central aperture through which said sheet metal sleeve and indexing cam extend, a retaining cover plate spaced from said insulating cover plate and having a closetting central aperture through which said sheet metal sleeve extends, said retaining cover plate serving to maintain said sleeve coaxial with said lamp socket and to retain said cams in position within said housing, and a pair of spring members having oppositely disposed detent nubs engageable with said indexing cam in the space between said insulating cover plate and retaining cover plate.

5. A rotary switch as claimed in claim 4 wherein the sheet metal sleeve has a longitudinal slot for indexing the cams.

6. A rotary switch as claimed in claim 4 wherein a turning knob is mounted on the sheet metal liner.

References Cited in the tile of this patent UNITED STATES PATENTS 2,710,323 Andrews June 7, 1955 

